Click the “tune” icon to the left of the https in the URL address field
In the pop-down menu, click Site settings
In the resulting Site Settings Details window, try > click on Delete data (might not exist?)
Next, in the same Site Settings Details window, click on Reset permissions (definitely exists)
Close the settings page.
Reload the https://www.youtube.com webpage
Click the “tune” icon
Make sure that JavaScript is Enabled
Tune icon:
In a Brave Browser New Window, go to: brave://settings/clearBrowserData and for Time range > All time, using Basic tab:
Enable Cookies and other site data
Enable Cached images and files
Click the Delete data button
Exit / Quit everything
Restart the computer
Create a new user Profile for Testing:
Create and use AN ADDITIONAL Brave Browser user Profile (Menu --> More tools --> Add profile) - only ← meaning: Do not have any other Brave Browser user Profile tabs/windows open.
When creating this new Brave Browser user Profile for test purposes
Do not import anything.
Do not add any extensions.
Do not allow/enable any Brave Browser “bells and whistles” such as Brave Rewards, Brave Talk, etc.
IF this test Brave Browser user Profile does not present your problem, then possibly, the profile that you have been using, has a problem . . . and that might be caused by one or more extensions, or too many tabs ← complex/conundrum.
Detailed info about testing - IF, in regard to memory and performance issues:
You have both options disabled: “Use graphics acceleration when available” and “Continue running background apps when Brave is closed.” Here’s a video tutorial that might help with YouTube performance.